I have noticed when I start the down swing , the shoulders & hips move simultaneously , the core moves all at once, no separating the hips & shoulders. Is this the correct way of thinking.
Yes, if you’ve wound up correctly (from top down), meaning shoulders start the backswing and wind from the top down… then on the downswing, we unwind from ground up. So, if you start with your hips on the downswing, as they move, the club head should move too. There should not be any “slack”. Everything should be wound like a rubber band. If you can start your hips on the downswing, and the upper body does not come along, you did not wind up correctly.